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SpaceX wants to fly some internet satellites closer to the ground

SpaceX revises its satellite internet initiative, Starlink, and it is now hoping to drive some of its spacecraft at a…

SpaceX revises its satellite internet initiative, Starlink, and it is now hoping to drive some of its spacecraft at a lower altitude than originally planned. In a new application to the Federal Communications Commission (FCC), SpaceX asks the agency to change its license so that more than 1,500 Starlink satellites can operate at an altitude of 600 kilometers lower than the company originally requested.

SpaceX claims that this change will make the space environment safer as it will be easier to get rid of these satellites at this new height when they run a little fuel or can no longer work properly in circulation. This update can also explain the unexpected behavior of two of SpaceX’s test satellites for Starlink, which remain in lower lanes than expected.

In March, the FCC licensed SpaceX’s license for the first phase of its ambitious Starlink initiative &#821

1; the company’s long-term plan to launch nearly 12,000 satellites in orbit to cover Internet coverage to the ground. Initially, the SpaceX FCC asked for permission to launch 4,425 satellites in lanes ranging between 1,110 and 1,325 kilometers high. But with this new filing, SpaceX requests that 1,584 of these satellites, which would work 1,110 kilometers, would work at 550 kilometers instead.

SpaceX says moving satellites to a lower altitude, which means it can do more with less. Originally, the company said it needed 1,600 satellites to work at 1,110 kilometers, but moving them lower means that the company could get the same result with 16 fewer spacecraft. And the lower height makes it easy to handle these satellites when they are ready in space. At this height, particles from the Earth’s atmosphere bombard the spacecraft faster, shoot them out of the orbit and drag them down to the planet. And on the way down they burn into the atmosphere.


One of SpaceX’s test satellites for Starlink, launched in February. Image: YouTube / SpaceX

Make sure these spacecraft come out of circulation in an early way, crucial because of the large number of vehicles SpaceX wants to put in orbit. A constellation size of Starlink can dramatically increase the number of operating satellites in space, which increases the risk of collisions in space. A recent NASA study claimed that 99 percent of these satellites will need to be unloaded reliably within five years of launch, or the risk of satellite collisions goes up quite a bit.

De-bana and satellite usually mean that the vehicle should be low enough with thrusters where the air particles and gravity of the soil pull the probe down to burn it. Now, with this new filing, SpaceX does not significantly move 1,584 of its satellites to get rid of them. The atmosphere of 550 kilometers will do the job within a few years. It is also useful if spacecraft fails in orbit. Satellites that fail at higher altitudes can be transformed into unoperative space junk that remains in circulation for long periods of time. At lower altitudes they can still fail, and the atmosphere will still swell them up on time.

And it can go a long way with the FCC, which expressed concern about how reliable these satellites will be and whether they will be interrupted on time. In fact, when the FCC approved the Starlink initiative, the Agency said it would be premature to grant SpaceX’s application based on the current waste disposal plan. “However, SpaceX received approval on condition that the company would provide an updated plan for how it would circumvent its satellites in time.

The new filing can also explain the behavior of two of SpaceX’s test satellites currently in circulation. In February, SpaceX launched successfully A pair of test satellites – TinTin A and B – intended to test the technology needed for internet-from-space attempts. However, the satellites did not reach their final planned paths in space. The goal was to introduce satellites at an altitude of 511 kilometers, and when all system on the vehicles had been checked out, SpaceX would then raise the pair at a height of 1,125 kilometers with the satellites on the brakes, an operation that would take about half a year to complete. The company detailed these plans in a letter to the FCC dated February 1, 2018, three weeks prior to launch


This graph, compiled by Jonathan McDowell with data from Sp ace_Track.org shows the orbital heights of TinTin A (red), TinTin B (blue) and PAZ (green) satellite launched with the Starlink test satellites. Apart from a certain maneuver, the satellites did not increase their pathways significantly as originally planned.
Image: Jonathan McDowell

However, satellites never left near 500 kilometers, according to Space_Track.org, a site that uses satellite tracking information provided by the Department of Defense. A diagram of duo mode over time shows that the satellites naturally become lower in their paths – probably because the particles from the atmosphere of the Earth drag them down, according to Jonathan McDowell, an astrophysicist at Harvard University who tracks spacecraft in circulation. In June and July, TinTin B increased its circulation slightly, indicating a slight burning of its built-in thrusters. TinTin A has barely moved, except for a small explosion on October 17th.

This led to speculation about a possible failure, first reported by Space Intel Report and SpaceX told the site that the satellites “Delivered to their intended circulation, communicated with ground stations, continue to communicate with ground stations and continue to work today. “

In today’s FCC archiving, SpaceX says it decided to change paths based on what it had learned from using the lower TinTin A and B. “Lower-level operation offers several attractive features both in nominal operation and unforeseen scenarios,” SpaceX wrote in archiving. The company says that this will simplify spacecraft construction and reduce latency in signals to just 15 milliseconds, which would be virtually unusable for almost all users, according to SpaceX.

But SpaceX acknowledges that there are some disadvantages of the lower lane. Because the atmosphere is somewhat denser at this height, it also means that spacecraft needs to work harder to stay in circulation and not let down to earth too early. It will also reduce the amount of Earth’s surface each satellite can cover at a given time, so SpaceX will need to change how the spacecraft transmits its signals.

The FCC still needs to approve SpaceX’s request, but the Commission has declared November “Space Month”, so it may be a bit of movement on this soon. Meanwhile, SpaceX assumes that it plans to launch its first series of Starlink satellites 2019. Under the terms of the FCC license, SpaceX must launch at least half of its 4,425 satellites (possibly 4,409 now) within six years to get its full constellation for use. In October, Reuters stated that SpaceX CEO Elon Musk had done a shakeup of Starlinks management to quickly meet the program deadlines.

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